Missed Diagnosis of Subarachnoid Hemorrhage in the Emergency Department

Abstract

Background and Purpose-Subarachnoid hemorrhage (SAH) can be devastating, yet its initial presentation may be limited to common symptoms and subtle signs, potentially leading to misdiagnosis. Little is known about population rates of misdiagnosis of SAH, or hospital factors that may contribute to it. We estimated the population-based rate of missed SAH among emergency department (ED) patients and examined its relationship with hospital characteristics. Methods-We studied persons admitted with a nontraumatic SAH to all Ontario hospitals over 3 years (April 2002 to March 2005. SAH was defined as missed if the patient had an ED visit related to the SAH (based on a prespecified definition) in the 14 days before admission. We examined the association between hospital teaching status and missed SAH and explored whether annual ED volume of SAH or CT availability explained this association. Results-Of 1507 patients diagnosed with SAH, 5.4% (95% CI, 4.3 to 6.6) had a missed diagnosis. The risk was significantly higher among patients triaged as low acuity (odds ratio 2.65; 95% CI, 1.46 to 4.80), as well as in nonteaching hospitals (adjusted odds ratio 2.12; 95% CI, 1.02, 4.44). Neither ED SAH volume nor on-site CT availability explained the effect of teaching status. Conclusions-About 1 in 20 SAH patients are missed during an ED visit. Lower acuity patients are at higher risk of misdiagnosis, suggesting the need for heightened suspicion among patients with minimal clinical findings. The risk is also greater in nonteaching hospitals, but this is not explained by the annual volume of SAHs seen in the ED or access to CT.

Validation of the Ottawa Subarachnoid Hemorrhage Rule in patients with acute headache

“…8 Physicians in the emergency department, when surveyed, have stated that 99% sensitivity is acceptable for a subarachnoid hemorrhage rule, a threshold that acknowledges the pitfall of pursuing diagnostic perfection at all cost. The narrow confidence bands of sensitivity for the Ottawa SAH Rule bracket this extremely high threshold, and the point estimate exceeds it.…”

“…6,7 However, a population-based study involving patients admitted to hospital through emergency departments in Ontario with a most responsible diagnosis of nontraumatic subarachnoid hemorrhage found that over 5% of confirmed subarachnoid hemorrhages were missed at initial presentation, especially in smaller hospitals. 8 Therefore, identifying which patients with headache require investigations to rule out this catastrophic diagnosis, and which do not, is a critical decision in emergency medicine.…”

Can Computed Tomography Angiography of the Brain Replace Lumbar Puncture in the Evaluation of Acute‐onset Headache After a Negative Noncontrast Cranial Computed Tomography Scan?

“…These issues may contribute to suboptimal work-ups and may account for the persistence of an basal rate of ''missed bleeds'' that was recently demonstrated to be 5% of acute headache patients in Canadian EDs. 39 …”

What Are the Unintended Consequences of Changing the Diagnostic Paradigm for Subarachnoid Hemorrhage After Brain Computed Tomography to Computed Tomographic Angiography in Place of Lumbar Puncture?

“…[1][2][3][4] Misdiagnosis can result in both poor patient outcomes and litigation. 3,5 The diagnostic algorithm for SAH is noncontrast brain computed tomographic study (CT), followed by lumbar puncture (LP) if the CT is normal or nondiagnostic.…”